Field of the Invention
The present invention relates to an element having an electromagnetic band gap (EBG) structure that prevents propagation of an electromagnetic wave in a specific frequency band.
Description of the Related Art
In recent years, an electromagnetic band gap technology for preventing propagation of an electromagnetic wave in a specific frequency band has been examined. An electromagnetic band gap structure exhibits a magnetic wall effect and can therefore be used to reduce the height of an antenna.
A general electromagnetic band gap structure is a mushroom structure in which conductor patches are arranged at a predetermined gap interval in an array pattern on the same plane, and conductive vias are connected from the conductor patches to ground conductors parallel to the conductor patches (see Japanese Patent Laid-Open No. 2002-510886). Japanese Patent Laid-Open No. 2010-010183 describes a structure of an electromagnetic band gap element including an open stub inserted between parallel plates.
The conventional mushroom type electromagnetic band gap structure is not suitable for incorporation in a compact electronic device because one cell is large. Note that according to, for example, the technique described in Japanese Patent Laid-Open No. 2010-010183, the electromagnetic band gap structure can be made small using an open stub. However, further size reduction is demanded.
The present invention has been made in consideration of the above-described problem, and reduces the size of an electromagnetic band gap structure.